Mounting evidence suggests that the superposition of anatomical clutter in a projection radiograph poses a major
impediment to the detectability of subtle lung nodules. Through decomposition of projections acquired at multiple kVp,
dual-energy (DE) imaging offers to dramatically improve lung nodule detectability and, in part through quantitation of
nodule calcification, increase specificity in nodule characterization. The development of a high-performance DE chest
imaging system is reported, with design and implementation guided by fundamental imaging performance metrics. A
diagnostic chest stand (Kodak RVG 5100 digital radiography system) provided the basic platform, modified to include:
(i) a filter wheel, (ii) a flat-panel detector (Trixell Pixium 4600), (iii) a computer control and monitoring system for
cardiac-gated acquisition, and (iv) DE image decomposition and display. Computational and experimental studies of
imaging performance guided optimization of key acquisition technique parameters, including: x-ray filtration, allocation
of dose between low- and high-energy projections, and kVp selection. A system for cardiac-gated acquisition was
developed, directing x-ray exposures to within the quiescent period of the heart cycle, thereby minimizing anatomical
misregistration. A research protocol including 200 patients imaged following lung nodule biopsy is underway, allowing
preclinical evaluation of DE imaging performance relative to conventional radiography and low-dose CT.
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